Electromechanical switch

ABSTRACT

An electromechanical switch includes a main contact provided with a number of main fixed contacts and a mobile main contact bridge; an auxiliary contact which precedes the main contact in the switch-on process and includes a number of auxiliary fixed contacts and a mobile auxiliary contact bridge; and a contact bridge carrier for actuating the main contact bridge and the auxiliary contact bridge. At least one of the contact parts is spring-mounted. The electromechanical switch has two stable positions of the auxiliary contact bridge or the auxiliary fixed contact. During the switching on process carried out by actuation of the contact bridge carrier via the auxiliary contact bridge or an auxiliary fixed contact in the first stable position, the auxiliary contact closes before the main contact, and during the switching off process by actuation of the contact bridge carrier in the opposite direction, the auxiliary contact with the auxiliary contact bridge or the auxiliary fixed contact in the second stable position opens before the main contact.

This application is the national phase under 35 U.S.C. § 371 of PCTInternational Application No. PCT/EP2004/002618 which has anInternational filing date of Mar. 12, 2004, which designated the UnitedStates of America and which claims priority on German Patent Applicationnumber DE 103 15 243.1 filed Apr. 3, 2003, the entire contents of whichare hereby incorporated herein by reference.

FIELD OF THE INVENTION

The invention generally relates to an electromechanical switchingdevice. In particular, it relates to a capacitor contactor.

BACKGROUND OF THE INVENTION

A switching device is known, for example, from DE 31 05 117 C2. Theswitching device known from DE 31 05 117 C2 has main contacts andleading contacts, also referred to as auxiliary contacts, which areinterconnected with series damping resistors given a capacitive load.

The same also applies, for example, to a capacitor contactor known fromDE 197 29 595 C1. When the switching device or capacitor contactor isswitched on, initially the auxiliary contacts close such that aconnected capacitor is initially pre-charged via the series dampingresistors. This weakens the switch-on current peak when the maincontacts close.

When the switching device is switched off, initially the main contactsopen and thus disconnect such that there is virtually no current.Overall, switch-on arcs thus predominantly occur at the main contacts.Since such switch-on arcs lead to changes in the contact pieces, therisk of wear is increased. Furthermore, when the switching device isswitched off, a relatively long arc-burning period results at the maincontacts, which form a zero-current interrupter, as a result of whichthe life of the device is shortened.

In order to counteract these disadvantages, the actuation of the maincontacts could be decoupled from the actuation of the auxiliarycontacts. This would, however, require the switching mechanism to have arelatively complex design.

SUMMARY OF THE INVENTION

An embodiment of the invention includes an object of specifying anelectromechanical, in particular electromagnetic, switching devicehaving a main contact and an auxiliary contact which leads during theswitch-on process, in particular for the purpose of reducing a switch-oncurrent peak.

The switching device of an embodiment can include a simple design andparticularly low wear owing to arcs on the main and/or auxiliarycontact.

This switching device of one embodiment has a main contact whichincludes a number of, generally two, main fixed contacts and a moveablemain contact bridge which can be connected to said main fixed contacts.In addition, the switching device has an auxiliary contact which closesearly during the switch-on process and which analogously comprises anumber of auxiliary fixed contacts and a moveable auxiliary contactbridge which can be connected to said auxiliary fixed contacts.

For the purpose of actuating both the main contact and the auxiliarycontact, a contact bridge holder or carrier is provided which ismechanically connected to the two contact bridges. At least one of thecontact parts (main fixed contact, main contact bridge, auxiliary fixedcontact and auxiliary contact bridge) is mounted in a sprung manner.

The auxiliary contact bridge or the at least one auxiliary fixed contactmay assume two stable positions which are defined, in the case of thebistable auxiliary contact bridge, relative to the contact bridge holderand, in the case of the bistable auxiliary fixed contact, relative to arigid structure of the switching device. As the switching device isswitched on, the auxiliary contact bridge or the auxiliary fixed contactis in the first position when the auxiliary contact closes and thusensures the leading switching behavior of the auxiliary contact inrelation to the main contact.

When the switching device is switched off, the auxiliary contact bridgeor the auxiliary fixed contact is in the second stable position at leastat the point in time at which the auxiliary contact opens. This alsoresults in a leading switching behavior of the auxiliary contact duringthe switch-off process, i.e. the auxiliary contact opens before the maincontact. The changeover between the first and the second stable positionof the auxiliary contact bridge or the auxiliary fixed contact or theauxiliary fixed contacts takes place with the actuation of the contactbridge carrier.

In one embodiment of the switching device which can be implementedsimply in design terms, the switching device is designed such that theauxiliary contact bridge can be electrically connected to the auxiliaryfixed contacts when the contact bridge holder is actuated only in thefirst position of the auxiliary contact bridge or the auxiliary fixedcontact. Whereas, in the second position of the auxiliary contact bridgeor the auxiliary fixed contact, the auxiliary contact bridge is alwaysseparated from the auxiliary fixed contacts irrespective of the positionof the contact bridge carrier.

When the electromechanical switching device is switched on, inaccordance with a preferred refinement the auxiliary contact bridge orthe auxiliary fixed contact is moved over from the first position to thesecond position by the contact bridge carrier being actuated once themain contact has closed, it is thus possible for the auxiliary contactto be open following completion of the switch-on process. During theswitch-off process, the auxiliary contact bridge or the auxiliary fixedcontact is thus initially in the second position. However, during theswitch-off process, the auxiliary contact bridge or the auxiliary fixedcontact, in turn triggered by the displacement of the contact bridgeholder, by interacting with a stop provided for this purpose onlychanges to the first position once the main contact has opened.

Owing to the changeover of the auxiliary contact bridge or the auxiliaryfixed contact during the switch-off process, the auxiliary contact isnot closed again. The auxiliary contact thus remains out of operationthroughout the switch-off process.

As a result of the fact that during the switch-off process only the maincontact switches, an arc across the main contact typically occurs notonly during the switch-on process but also during the switch-offprocess. In addition to protecting the auxiliary contacts, this has theadvantage that any softened contact mass present on the main contact andformed by the switch-on arc melts over again, as a result of which thereis a reduced risk of wear and thus the life of the switching device islengthened. A simple design for the switching device is achieved by boththe main contact bridge and the auxiliary contact bridge remainingcoupled to the contact bridge holder during all switching processes.

A space-saving design for the switching device is preferably implementedby the main contact bridge and the auxiliary contact bridge beingarranged at least approximately parallel to one another. The contactbridge holder is preferably arranged perpendicular to one of the contactbridges, in particular to the two contact bridges. In a manner known perse, the contact bridge is furthermore preferably mounted in a sprungmanner in the contact bridge carrier, in particular using a springarranged within the cross section of the contact bridge carrier. Thedesign of the switching device in this regard largely corresponds interms of embodiments, which have the mentioned features, to the designof a switching device which is known, for example, from DE 31 05 117 C2.

However, the mounting of the auxiliary contact bridge in or on thecontact bridge carrier and/or the mounting of the auxiliary fixedcontacts in the switching device differs from this known switchingdevice. The auxiliary contact bridge in the switching device known fromDE 31 05 117 C2 can only assume a single stable position, namely pushedby spring force in the direction of the main contact bridge. However,the switching device according to an embodiment of the invention, inaccordance with a first alternative, includes two defined stablepositions of the auxiliary contact bridge. In this case, the auxiliarycontact bridge can be displaced, for example, relative to the contactbridge holder perpendicular to the contact bridge holder and, inparticular with the assistance of spring force, can be latched into twodifferent positions on the contact bridge holder.

However, in accordance with a particularly advantageous embodiment, theauxiliary contact bridge is mounted in or on the contact bridge carrierat a suspension point, which cannot be displaced relative to the contactbridge carrier, in a very simple manner in design terms. In this case,the auxiliary contact bridge must have an intrinsic ability to move atleast slightly in order to be able to assume two different stablepositions. The auxiliary contact bridge is preferably in the form of asnap-action spring which is mounted approximately centrally on thecontact bridge carrier.

In accordance with a second alternative, the auxiliary contact bridge isof rigid design and is mounted in the contact bridge carrier such thatit cannot be displaced. However, the auxiliary fixed contact, preferablytwo auxiliary fixed contacts arranged symmetrically with respect to thecontact bridge carrier, is formed in a resilient manner with twopossible stable positions. With this embodiment, the auxiliary fixedcontact is advantageously in the form of a snap-action spring. However,an intrinsically rigid auxiliary fixed contact may also be providedwhich can assume two stable positions owing to the fact that it ismounted in the housing of the switching device such that it can move,for example be displaced or pivoted.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the invention will be explained in more detailbelow with reference to a drawings, in which:

FIGS. 1 a to 1 d show schematic illustrations of a first embodiment ofan electromechanical switching device during the switch-on process,

FIGS. 2 a to 2 d show schematic illustrations of the electromechanicalswitching device shown in FIGS. 1 a to 1 d during the switch-offprocess,

FIGS. 3 a to 3 d show schematic illustrations of a second embodiment ofan electromechanical switching device during the switch-on process, and

FIGS. 4 a to 4 d show schematic illustrations of the electromechanicalswitching device shown in FIGS. 3 a to 3 d during the switch-offprocess.

Mutually corresponding parts or parts having the same function areidentified by the same reference numerals in all of the figures.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

FIGS. 1 a to 1 d and 2 a to 2 d show very simplified cross-sectionaldetail illustrations of an electromechanical switching device 1 in theform of a capacitor contactor in different switching states. Theswitching device 1 has a main contact 2 having a main contact bridge 3and main fixed contacts 4 as well as an auxiliary contact 5 having anauxiliary contact bridge 6 and auxiliary fixed contacts 7. A contactbridge carrier 8 is provided for the purpose of actuating the contactbridges 3, 6.

The main contact bridge 3 is mounted in the contact bridge carrier 8such that it can be displaced by means of a compression spring 9. By aload being applied via the compression spring 9, the main contact bridge3 can assume a single stable position relative to the contact bridgecarrier 8, which is also referred to as a slide, namely pushed in thedirection of the main fixed contacts 4.

The auxiliary contact bridge 6, in contrast to the main contact bridge3, is connected to the contact bridge carrier 8 at a point which isfixed relative to the contact bridge carrier 8, namely at the suspensionpoint 10. The auxiliary contact bridge 6 is in the form of a snap-actionspring which can assume two stable positions. In order to change overbetween these two stable positions of the auxiliary contact bridge 6,firstly, in the illustration below the auxiliary contacts 6, theauxiliary fixed contacts 7 and secondly, in the illustration above theauxiliary contact bridge 6, two stops 11 are provided.

FIG. 1 a shows the switching device 1 in the switched-off state. Theauxiliary contact bridge 6 is located in the first position. When theswitching device 1 is switched on by the contact bridge carrier 8 beingdisplaced, at the bottom in the illustration, initially the auxiliarycontact 5 closes (FIG. 1 b).

In the further course of the contact bridge carrier 8 being actuated,the auxiliary contact bridge 6 temporarily assumes an unstableintermediate position. In this case the auxiliary contact 5 remainsclosed. With the auxiliary contact 5 closed, the main contact 2 now alsocloses (FIG. 1 c). If the contact bridge carrier 8 is displaced furtherin the direction of the switch-on position as the spring 9 is compressed(FIG. 1 d), also referred to as resilience, the auxiliary contact bridge6, which is mounted at the suspension point 10 such that it cannot bedisplaced relative to the contact bridge carrier 8, snaps around, i.e.assumes its second stable position. In this second stable position ofthe auxiliary contact bridge 6, in the exemplary embodiment illustratedthe auxiliary contact 5 is always open irrespective of the position ofthe contact bridge carrier 8.

When the switching device 1 is switched on, only the main contact 2 isthus closed. As a deviation from this embodiment, the auxiliary contact5 may likewise remain closed even when the main contact 2 is closed andmay only open during the switch-off process, before the main contact 2,i.e. such that it leads said main contact 2.

With reference to FIGS. 2 a to 2 d, the switch-off process of theswitching device 1 will be explained below. The state of the switchingdevice shown in FIG. 2 a corresponds to the state shown in FIG. 1 d. Ifthe contact bridge carrier 8 is displaced in the direction of theswitch-off position, upwards in the illustration, initially theauxiliary contact 5 opens as long as it was not already open (as in theexemplary embodiment), and then the main contact 2 (FIG. 2 c). Theauxiliary contact bridge 6 hits against the stop 11 as the main contact2 opens and, triggered by the opening movement of the contact bridgecarrier 8, snaps back around into the first stable state (FIG. 2 d).However, the auxiliary contact bridge 6 is in this case already liftedso far up from the auxiliary fixed contacts 7 that the auxiliary contact5 no longer closes. The auxiliary contact 5 thus remains open throughoutthe switch-off process in the exemplary embodiment. The switchingposition shown in FIG. 2 d corresponds to the switching position shownin FIG. 1 a.

FIGS. 3 a to 3 d and 4 a to 4 d show an alternative design for aswitching device 1 which differs from the switching device shown inFIGS. 1 a to 2 d in terms of the configuration of the auxiliary contact5. With the switching device shown in FIGS. 3 a to 4 d, the auxiliarycontact bridge 6 is of rigid design, whereas the auxiliary fixedcontacts 7 are of resilient design and can assume two stable positions.The auxiliary fixed contacts 7 are in this case clamped at one end inthe housing (not shown) of the switching device 1.

FIGS. 3 a to 3 d show the switch-on process of the switching device 1.In their first stable position (FIG. 3 a), the auxiliary fixed contacts7 are bent slightly towards the auxiliary contact bridge 6 which isarranged above them in the illustration and is rigid and straight. Thechangeover to the second stable position of the auxiliary fixed contacts7 (FIG. 3 d) takes place in an analogous manner to the switching processshown in FIGS. 1 a to 1 d. If the contact bridge carrier 8 is located inthe closed final position (FIG. 3 d), the auxiliary contact 5 is open inthe exemplary embodiment illustrated. Alternatively, the auxiliarycontact 5 could, however, also remain closed.

The switching position shown in FIG. 4 a, which characterizes thebeginning of the switch-off process, corresponds to the switchingposition shown in FIG. 3 d. During the switch-off process, the stops 11,which are in this case fitted to the contact bridge carrier 8, come intooperation. By use of the stops 11, the auxiliary fixed contacts 7 aremoved over from their second stable position, in which they aredeflected in the direction of the main contact 2 (FIG. 4 a), into theirfirst stable position (FIG. 4 d). The auxiliary contact 5 remains openwhen the switching device 1 is switched off, analogously to FIGS. 2 a to2 d. As a deviation from this, an opening of the auxiliary contact 5could also only be provided during the switch-off process, but in anycase before the opening of the main contact 2. The switching positionshown in FIG. 4 d corresponds to the switching position shown in FIG. 3a.

Exemplary embodiments being thus described, it will be obvious that thesame may be varied in many ways. Such variations are not to be regardedas a departure from the spirit and scope of the present invention, andall such modifications as would be obvious to one skilled in the art areintended to be included within the scope of the following claims.

1. An electromechanical switching device, comprising: a main contactincluding a number of main fixed contacts and a moveable main contactbridge; an auxiliary contact which leads during the switch-on processand which includes a number of auxiliary fixed contacts and a moveableauxiliary contact bridge; and a contact bridge carrier, provided foractuating the main contact bridge and the auxiliary contact bridge,wherein at least one of the contacts are mounted in a sprung manner,wherein two stable positions of the auxiliary contact bridge relative tothe contact bridge carrier are provided, and when the switching deviceis switched on, the auxiliary contact bridge in its first stableposition closing the auxiliary contact which leads the main contact bythe contact bridge carrier being actuated, and when the switching deviceis switched off, the auxiliary contact with the auxiliary contact bridgelocated in the second stable position opening before the main contact bythe contact bridge carrier being actuated in the opposite direction. 2.The switching device as claimed in claim 1, wherein, during theswitch-on process, the auxiliary contact bridge is movable over into itssecond stable position via the mechanical action of the auxiliary fixedcontacts on the auxiliary contact bridge.
 3. The switching device asclaimed in claim 2, wherein, during the switch-on process, the change,which is triggered by the actuation of the contact bridge carrier,between the first and the second stable position of the auxiliarycontact bridge once the main contact has closed, can trigger an openingof the auxiliary contact.
 4. The switching device as claimed in claim 1,wherein, during the switch-off process, the auxiliary contact bridge ismovable over into its first stable position via the mechanical action ofat least one stop on the auxiliary contact bridge.
 5. The switchingdevice as claimed in claim 1, wherein the auxiliary contact bridge is inthe form of a snap-action spring.
 6. An electromechanical switchingdevice, comprising: a main contact including a number of main fixedcontacts and a moveable main contact bridge; an auxiliary contact whichleads during the switch-on process and which includes a number ofauxiliary fixed contacts and a moveable auxiliary contact bridge; and acontact bridge carrier for actuating the main contact bridge and theauxiliary contact bridge, wherein at least one of the contacts ismounted in a sprung manner, wherein two stable positions of at least oneauxiliary fixed contact are provided, and when the switching device isswitched on, the auxiliary contact bridge making contact with theauxiliary fixed contact in its first stable position by the contactbridge carrier being actuated and in the process closing the auxiliarycontact (before the main contact, and when the switching device isswitched off, the auxiliary contact with the auxiliary fixed contactlocated in the second stable position opening before the main contact bythe contact bridge carrier being actuated in the opposite direction. 7.The switching device as claimed in claim 6, wherein, during theswitch-on process, the auxiliary fixed contact is movable over into itssecond stable position via the mechanical action of the auxiliarycontact bridge on the auxiliary fixed contact.
 8. The switching deviceas claimed in claim 7, wherein, during the switch-on process, thechange, which is triggered by the actuation of the contact bridgecarrier, between the first and the second stable position of theauxiliary fixed contact once the main contact has closed, can trigger anopening of the auxiliary contact.
 9. The switching device as claimed inclaim 6, wherein, during the switch-off process, the auxiliary fixedcontact movies movable over into its first stable position viamechanical action of at least one stop on the auxiliary fixed contact.10. The switching device as claimed in claim 6, wherein the auxiliaryfixed contact is in the form of a snap-action spring.
 11. The switchingdevice as claimed in claim 6, wherein two auxiliary fixed contacts arearranged at least approximately symmetrically with respect to thecontact bridge carrier.
 12. The switching device as claimed in claim 1,wherein the main contact bridge and the auxiliary contact bridge arearranged at least approximately parallel to one another.
 13. Theswitching device as claimed in claim 1, wherein at least one of thecontact bridges is arranged at least approximately perpendicular to thecontact bridge carrier.
 14. The switching device as claimed in claim 1,wherein the auxiliary contact bridge is mounted in the contact bridgecarrier at a suspension point, which cannot be displaced relative to thecontact bridge carrier.
 15. The switching device as claimed in claim 2,wherein, during the switch-off process, the auxiliary contact bridge ismovable over into its first stable position via the mechanical action ofat least one stop on the auxiliary contact bridge.
 16. The switchingdevice as claimed in claim 3, wherein, during the switch-off process,the auxiliary contact bridge is movable over into its first stableposition via the mechanical action of at least one stop on the auxiliarycontact bridge.
 17. The switching device as claimed in claim 7, wherein,during the switch-off process, the auxiliary fixed contact moviesmovable over into its first stable position via mechanical action of atleast one stop on the auxiliary fixed contact.
 18. The switching deviceas claimed in claim 8, wherein, during the switch-off process, theauxiliary fixed contact movies movable over into its first stableposition via mechanical action of at least one stop on the auxiliaryfixed contact.
 19. The switching device as claimed in claim 6, whereinthe main contact bridge and the auxiliary contact bridge are arranged atleast approximately parallel to one another.
 20. The switching device asclaimed in claim 6, wherein at least one of the contact bridges isarranged at least approximately perpendicular to the contact bridgecarrier.
 21. The switching device as claimed in claim 6, wherein theauxiliary contact bridge is mounted in the contact bridge carrier at asuspension point, which cannot be displaced relative to the contactbridge carrier.